Acylation Process

ABSTRACT

The invention concerns a process for the manufacture of an acylated polymer composition comprising amylose and/or amylopectin, comprising a pre-treatment step in the presence of an acid, a salt and a polycarboxylic acid, subsequent acylation and, preferably, a post-treatment step with an acid. The products obtained are useful as additives in inks, varnishes, lacquers, coatings, thickeners, adhesives or binders.

The present invention relates to an acylation process of polymercompositions comprising amylose and/or amylopectin, acylated polymercompositions comprising amylose and/or amylopectin products and the useof such acylated products in certain applications.

Acylated polymer compositions, like acetylated starch, are importantprocessed renewable raw materials which can be used in a wide range ofindustrially applied polymers. They can be applied for example in inks(e.g. WO2012059), excipients in pharmaceutics (e.g. WO11011217) andfoodstuffs (e.g. US2013236624).

A common process for the acylation of polymer compositions comprisingamylose and/or amylopectin, such as starch, is the reaction of such apolymer composition with an acetylating agent, for example a carboxylicacid anhydride, which reacts with the hydroxyl functions of the polymerto form the acylated polymer composition. The physical properties of theacylated polymer composition, specifically acylated starch, aredifficult to control in the acylation process. It is therefore an objectof the present invention to provide an improved process for theacylation of polymer compositions comprising amylose and/or amylopectin,such as starch. An acylated polymer composition comprising amyloseand/or amylopectin with superior physical properties is another objectof the present invention. It is also the object of the present inventionto provide a process for the manufacture of inks, varnishes, lacquers,coatings, thickeners, adhesives or binders using the acylated polymercomposition comprising amylose and/or amylopectin with superior physicalproperties as ingredient.

It was now found that the physical properties of acylated polymercompositions, such as acylated starch, may effectively be controlled bytreating the starch before acylation with an aqueous phase comprisingone additive chosen from the group consisting of at least one acid Ahaving a pKa of equal to or less than 4.8 at 25° C. and an enzyme, andadditionally at least one salt and at least one polycarboxylic acid. Thephysical properties can further be controlled in an additional stepafter the acylation step, by treating the acylated polymer with at leastone acid A′ with a pKa of equal to or less than 4.8 at 25° C., in thepresence of water.

Consequently, in its broadest embodiment, the invention concerns aprocess for the manufacture of an acylated polymer compositioncomprising amylose and/or amylopectin having a viscosity of equal to orgreater than 77 mPas (10 w % in Triacetin at 30° C.) which comprises

-   -   (a) pre-treating a polymer composition comprising amylose and/or        amylopectin with an aqueous phase comprising one additive chosen        from the group consisting of at least one acid A having a pKa of        equal to or less than 4.8 at 25° C. and an enzyme, and        additionally at least one salt and at least one polycarboxylic        acid.    -   (b) reacting the pre-treated polymer composition with an        acylating agent to provide an acylated polymer composition        comprising amylose and/or amylopectin.

The pre-treatment step in the process allows for efficient swelling ofthe polymer composition, therefore providing pre-treated polymer whichcan be efficiently acylated. Additionally, adjustment of the viscositycan be effected in the pre-treatment step. This is further detailedbelow. Preferred polymer compositions comprising amylose and/oramylopectin are starches.

In a preferred embodiment, the invention concerns a process for themanufacture of an acylated polymer composition comprising amylose and/oramylopectin having a viscosity of from equal to or greater than 77 mPas(10 w % in Triacetin at 30° C.) which comprises

-   -   (a) pre-treating a polymer composition comprising amylose and/or        amylopectin with an aqueous phase comprising at least one        additive chosen from the group consisting of at least one acid A        having a pKa of equal to or less than 4.8 at 25° C. and an        enzyme, and additionally at least one salt and at least one        polycarboxylic acid.    -   (b) reacting the pre-treated polymer composition with an        acylating agent to provide an acylated polymer composition        comprising amylose and/or amylopectin, and    -   (c) reacting the acylated polymer composition obtained in        step (b) with at least one acid A′ with a pKa of equal to or        less than 4.8 at 25° C., in the presence of water.

In step (c) according to the process in of the preferred embodiment, apartial hydrolysis takes place, by which the DS controlled. Theresulting products have an improved EtOH tolerance. DS and EtOHtolerance are explained further below.

The invention further concerns an acylated polymer compositioncomprising amylose and/or amylopectin, which is obtainable by such aprocess.

Another object of the invention is an acylated polymer compositioncomprising amylose and/or amylopectin, having a degree of substitution(DS) in the range of from 2.1 to 2.9, wherein the viscosity of polymercomposition is equal to or greater than 77 mPas (10 w % in Triacetin at30° C.) and which has a EtOH tolerance of equal to or lower than 60%(v/v).

Preferred acylated polymer composition comprising amylose and/oramylopectin are starches.

A process for the manufacture of inks, varnishes, lacquers, coatings,thickeners, adhesives or binders, using acylated starch which has beenprovided by the claimed acylation process, and/or the acylated polymercomposition comprising amylose and/or amylopectin obtainable by theclaimed process and/or the acylated polymer composition comprisingamylose and/or amylopectin having a degree of substitution (DS) in therange of from 2.1 to 2.9, wherein the viscosity of polymer is equal toor greater than 77 mPas (measured in a 10 w % in Triacetin solution at30° C.) and which has an EtOH tolerance of equal to or lower than 60%(v/v), as an ingredient, is also claimed in the present invention. EtOHis intended to denote ethanol.

In the present specification, the plural form and the singular form areused interchangeably. Thus, it should be understood that the plural formalso includes the singular form and vice-versa, unless otherwiseindicated herein or clearly contradicted by context. For example, “acid”denotes a single acid or a mixture of two or more acids. As anotherexample, “starch” denotes a single starch from a single source,amylopectin/amylose composition and/or modification as well as a mixtureof two or more starches of different sources, amylopectin/amylosecompositions, modifications etc.

Polymer compositions comprising amylose and/or amylopectin generally canconsist of isolated fractions of amylose or isolated fractions ofamylopectin, or a mixture of amylose and amylopectin. Starch is apreferred polymer composition which comprises essentially a mixture ofamylose and amylopectin. Each of these materials are composed ofD-glucose units linked to one another via α-(1-4) and α-(1-6) linkages,the latter being responsible for the branches in the structure of themolecule. The ratio between the amounts of amylose and amylopectindepends on the source of the polymer, e.g. starch. According to thepresent invention, the starch employed as starting material for theacylation process can comprise predominantly amylose or, conversely,predominantly amylopectin (waxy starch). Generally, whole starch and/orisolated fractions of amylose and/or isolated fractions of amylopectincan be used. According to the present invention, the term “polymercomprising amylose and/or amylopectin” includes its preferred form,namely “starch”. The starches can be derived from any native source,wherein native relates to the fact that said starch is found in nature.Unless specifically distinguished, references to starch in thisspecification are meant to include their corresponding flours, which arestill containing proteins, such as wheat gluten (hereinafter “starch”).In the present invention, a single several or starch sources can beused. The starch may also be combined out of several sources, isolatedamylose fractions and/or amylopectin fractions, and/or derivatives likechemically or physically modified starch, which will be explainedfurther below. Typical sources for the starches are cereals, tubers,roots, legumes, fruit starches and hybrid starches. Suitable sourcesinclude but are not limited to, millet, pea, potato, sweet potato,maize, sorghum, banana, barley, wheat, rice, sago, amaranth, tapioca,arrowroot and cannay. Preferred sources according to the presentinvention are selected from the group consisting of tubers, legumes orcereals. Even more preferably, the starch source is selected from thegroup consisting of pea, potato, sweet potato, wheat and maize. Mostpreferably, maize with a high amylopectin content (waxy maize) is usedas starch source. Also suitable are starches derived from a plantobtained by breeding techniques including crossbreeding, translocation,inversion, transformation or any other method of gene or chromosomeengineering to include variations thereof.

In another embodiment of the present invention, starch is used asstarting material which is chemically and/or physically modified.

“Chemically modified starch” is intended to denote in particular thepartial chemical modification of the hydroxyl-groups in amylose and/oramylopectin. Generally, chemically modified starches which can beselected as starting material according to the present invention can beclassified as crosslinked starches, partially acetylated starches,partially etherified starches like hydroxyethylated, hydroxypropylatedand methylated starches, inorganically esterified starches, cationic,anionic (like carboxymethyl starch), oxidized starches, zwitterionicstarches, starches modified by enzymes. The preferred chemicallymodified starch is a partially hydroxypropylated starch.

In one embodiment of the present invention, the modified starch ismaltodextrin.

“Physically modified starch” is intended to denote a starch that hasbeen modified by a physical method. Generally, physical methods for themodification of starch include heat treatment, heat-moisture treatment,annealing, retrogradation, freezing, mechanical treatment, ultra highpressure treatment, gelatinization, glow discharge plasma treatment andosmotic pressure treatment.

According to the present invention, mixtures of any of the abovementioned starches, modified starches and/or flours, derived from anysource, are also within the scope of this invention. For the sake ofsimplicity, the expression “starch” is intended to denote equally any ofthe starches, modified starches, flours and or/their mixtures, derivedfrom any source with any amylopectin/amylose ratio.

In one embodiment of the invention, the employed starch has an amylosecontent of equal to or greater than 0% and equal to or lower than 60%,based on the sum of weights of amylose and amylopectin. Preferably, theemployed starch has an amylose content of from 0% to 40%. Especiallypreferably, the employed starch has an amylose content of from 0% to20%.

The term “acylation of a polymer composition comprising amylose and/oramylopectin” is intended to denote the reaction of free hydroxyl groupsof the glucose units of a polymer composition comprising amylose and/oramylopectin with an acylating agent to form a corresponding acylatedpolymer composition comprising amylose and/or amylopectin. Principally,polymer composition comprising amylose and/or amylopectin correspond toformula ST(OH)₃ and reacts with a acylating agent to the correspondentacylated polymer composition comprising amylose and/or amylopectin offormula ST(OH)_(3-x)(OC(O)R)_(x). “ST” denotes the amylose and/oramylopectin polymer backbone. In the formula ST(OH)_(3-x)(OC(O)R)_(x), xdenotes the DS (degree of substitution) of the hydroxyl groups in thestarch. The DS is the average amount of acylated hydroxyl groups perglucose entity. Generally, the DS of the final acylated polymercomposition comprising amylose and/or amylopectin according to thepresent invention is from 2.1 to 2.9. Preferably, the DS of the finalacylated polymer composition comprising amylose and/or amylopectin isgreater than 2.1. More preferably, the DS of the final acylated polymercomposition comprising amylose and/or amylopectin is equal to or greaterthan 2.2. Most preferably, the DS of the final acylated polymercomposition comprising amylose and/or amylopectin is equal to or greaterthan 2.3. Preferably, the DS of the final acylated polymer compositioncomprising amylose and/or amylopectin is equal to or less than 2.9. Morepreferably, the DS of the final acylated polymer composition comprisingamylose and/or amylopectin is equal to or less than 2.85. If desired,the DS of the final acylated polymer composition comprising amyloseand/or amylopectin is equal to or less than 2.7. In a most preferredembodiment of this invention, the DS of the final acylated polymercomposition comprising amylose and/or amylopectin is from 2.3 to 2.85.

In the case that a partially chemically modified polymer compositioncomprising amylose and/or amylopectin is used, x relates to the freehydroxyl groups of the polymer composition comprising amylose and/oramylopectin. In this case, a modified polymer composition comprisingamylose and/or amylopectin ST(OR^(m))_(z)(OH)(_(3-z)), wherein R^(m) isintended to denote the chemically modifying group of the startingmaterial such as methyl, reacts with an acylating agent to thecorrespondent acylated polymer composition comprising amylose and/oramylopectin of formula ST(OR^(m))_(z)(OH)_((3-z)-x)(OC(O)R)_(x). In thisequation, R^(m) is a chemically modifying group which, in a first aspectdoes not bear a hydroxyl group. Thus, in the case that chemicallymodified polymer composition comprising amylose and/or amylopectin isused as starting material, the DS is meant to denote the sum of z and x,DS=x+z. For the sake of simplicity, DS is meant to denote x forchemically not modified starting material or chemically modifiedstarting material when in a second aspect R^(m) bears one hydroxylgroup, for example hydroxypropyl, and DS=x+z in chemically modifiedstarting material, when in a second aspect R^(m) bears not hydroxylgroup, throughout the specification.

According to the present invention, R is a linear or branched aliphaticor cycloaliphatic group containing 1 to 18 carbon atoms, an araliphaticgroup containing 7 to 12 carbon atoms or an aromatic group containing 6to 12 carbon atoms. R can optionally be substituted by one or morehalogens, preferably fluorine, NO₂, phenyl, C(O)OR¹, OR¹ or an aromaticgroup containing to 12 carbon atoms substituted by a C₁₋₆ aliphaticgroup. R¹ is a C₁-C₄ alkyl group, which can optionally be substituted byone or more halogens, preferably fluorine.

An acylating agent is intended to denote a reactant which is capable ofreacting with the hydroxyl groups of the glucose units of a polymercomposition comprising amylose and/or amylopectin, thereby transferringan acyl group —C(O)R, —C(O)R′ and/or —C(O)R″ to form the acylatedpolymer composition comprising amylose and/or amylopectin. Acylatingagents may be, for example, carboxylic acid anhydrides (RC(O))₂O, butalso unsymmetrical carboxylic acid anhydrides corresponding to theformula (RC(O))(R″C(O))O. Other suitable acylating agents comprisecarboxylic acid halides or carbonylimidazoles.

According to one embodiment, the polymer composition comprising amyloseand/or amylopectin is pre-treated in step (a) with an aqueous phasecontaining an acid A having a pKa of equal to or less than 4.8 at 25° C.and additionally at least one salt and at least one polycarboxylic acid.Generally, the acid A having a pKa of equal to or less than 4.8 at 25°C. is selected from the group consisting of mineral acids, sulfonicacids and carboxylic acids. The acid A can be either monoprotic orpolyprotic. If acid A is polyprotic, at least pKa₁ is equal to or lessthan 4.8 at 25° C. Preferably, acid A is selected from the groupconsisting of sulfuric acid, amidosulfonic acid, methane sulfonic acid,benzene sulfonic acid or phosphoric acid. Most preferably, acid A isselected from the group consisting of sulfuric acid and benzene sulfonicacid. Generally, more than one acid A can be present in step (a). Inthis embodiment, acid A is added in step (a) in an amount of equal to orgreater than 0.001 weight %, based on the amount of polymer compositioncomprising amylose and/or amylopectin. For this purpose, the weight ofany moisture present in the polymer composition comprising amyloseand/or amylopectin before step (a) is not taken into account whencalculating the ratio of acid to polymer composition comprising amyloseand/or amylopectin. If more than one acid A is added in step (a), thesum of weight percentages of the more than one acids A is the same asthe weight percentage denoted in the specification for a single acid A.Preferably, acid A is added in step (a) in an amount of equal to orgreater than 0.01 weight %. Most preferably, acid A is added in step (a)in an amount of equal to or greater than 0.1 weight %. Generally, acid Ais added in step (a) in an amount of equal to or less than 5 weight %.Preferably, acid A is added in step (a) in an amount of equal to or lessthan 3 weight %. Most preferably, acid A is added in step (a) in anamount of equal to or less than 1.5 weight %. In a most preferredembodiment of this invention, the amount of acid A added in step (a) isfrom 0.3 to 1.3 weight %.

According to another embodiment, the polymer composition comprisingamylose and/or amylopectin is pre-treated in step (a) with an aqueousphase containing an enzyme and additionally at least one salt and atleast one polycarboxylic acid. Generally, the enzyme is selected fromthe group of hydrolases. Preferably, the enzyme is an amylase. Theamylase can be of human, animal or plant origin, bacterial source,fungicidal source or genetically engineered microorganism source.Preferably, the amylase is selected from the group comprisingglucoamylase, α-amylase, β-amylase and γ-amylase. A very preferredenzyme is the alpha-amylase Termamyl™. The enzyme used as additive instep (a) is added in an amount equal to or greater than 5 U (enzymeunit) per g polymer composition. Preferably, the enzyme used as additivein step (a) is added in an amount equal to or greater than 10 U (enzymeunit) per g polymer composition. Even more preferably, the enzyme usedas additive in step (a) is added in an amount equal to or greater than15 U (enzyme unit) per g polymer composition. Generally, the enzyme usedas additive in step (a) is added in an amount equal to or lower than 200U (enzyme unit) per g polymer composition. Preferably, the enzyme usedas additive in step (a) is added in an amount equal to or lower than 150U (enzyme unit) per g polymer composition. More preferably, the enzymeused as additive in step (a) is added in an amount equal to or lowerthan 100 U (enzyme unit) per g polymer composition. Most preferably, theenzyme used as additive in step (a) is added in an amount from 20 to 90U/g polymer composition. Generally, enzyme degradation in step (a) isstopped by the addition of a 1 to 15% aqueous mineral acid, preferablyaqueous hydrochloric acid.

According to the present invention, a polycarboxylic acid present instep (a). The term “polycarboxylic acid” is intended to denote acarboxylic acid bearing at least two carboxylic acid groups. Thepolycarboxylic acid comprises from 2 to 12 carbon atoms which can besubstituted, additionally to the at least two carboxylic acid groups,with one or more substituents chosen from the group comprising primary,secondary or tertiary amines, amides, nitro, nitrile, amido, mercapto,optionally substituted or unsubstituted alkyl, optionally substituted orunsubstituted aryl, keto-group and aldehyde-group. In the case that theoptionally substituted or unsubstituted polycarboxylic acid has one ormore stereocenters, the term “polycarboxylic acid” as used in thepresent invention includes all racemates, enantiomers, diastereomers ormixtures of any of the foregoing. Generally, more than onepolycarboxylic acid can be present in step (a).

Preferably, the polycarboxylic acid of step (a) is selected from thegroup consisting of oxalic acid, malonic acid and succinic acid,glutaric acid and adipic acid. Most preferably, the polycarboxylic acidis malonic acid.

According to the present invention, the polycarboxylic acid is added instep (a) in an amount of equal to or greater than 0.01 weight %, basedon the amount of starch. For this purpose, the weight of any waterpresent in the starch before step (a) is not taken into account whencalculating the ratio of polycarboxylic acid to starch. If more than onepolycarboxylic acid is added in step (a), the sum of weight percentagesof the more than one polycarboxylic acids is the same as the weightpercentage denoted above for a single polycarboxylic acid. Preferably,the polycarboxylic acid is added in step (a) in an amount of equal to orgreater than 0.1 weight %. Most preferably, the polycarboxylic acid isadded in step (a) in an amount of equal to or greater than 0.3 weight %.Generally, polycarboxylic acid is added in step (a) in an amount ofequal to or less than 5 weight %. Preferably, the polycarboxylic acid isadded in step (a) in an amount of equal to or less than 2.5 weight %.Most preferably, the polycarboxylic acid is added in step (a) in anamount of equal to or less than 1 weight %. In a most preferredembodiment of this invention, the amount of the polycarboxylic acidadded in step (a) is from 0.35 to 0.9 weight %.

According to the present invention, a salt is present in step (a). Themetal cation species of the salt is preferably chosen from groups 1, 2,11 or 12 of the periodic system. Preferably, the salt cation is chosenfrom the group consisting of Mg2+, K+, Zn2+, Na+, Li+, Cu2+ and Ca2+,wherein Mg2+ is especially preferred. The anion species of the salt isselected from anions derived from mineral acids or organic acids,wherein the anion is preferably selected from the group consisting ofsulfate, nitrate, chloride, carbonate, acetate and malonate. Especiallypreferred is carbonate. A very preferred salt in this embodiment isMgSO4, another very preferred salt is MgCO₃. According to the presentinvention, the salt is added in step (a) in an amount of equal to orgreater than 0.005 weight %, based on the amount of starch. For thispurpose, the weight of any water present in the starch before step (a)is not taken into account when calculating the ratio of salt to starch.If more than one salt is added in step (a), the sum of weightpercentages of the more than one salts is the same as the weightpercentage denoted above for a single salt. Preferably, the salt isadded in step (a) in an amount of equal to or greater than 0.05 weight%. Most preferably, the salt is added in step (a) in an amount of equalto or greater than 0.15 weight %. Generally, salt is added in step (a)in an amount of equal to or less than 2.5 weight %. Preferably, the saltis added in step (a) in an amount of equal to or less than 1.2 weight %.Most preferably, the salt is added in step (a) in an amount of equal toor less than 1 weight %. In a most preferred embodiment of thisinvention, the amount of the salt added in step (a) is from 0.2 to 0.8weight %.

In step (a), the polymer composition comprising amylose and/oramylopectin is generally pre-treated at a temperature of equal to orgreater than 20° C. More preferably, the pre-treatment temperature isequal to or greater than 40° C. Even more preferably, the pre-treatmenttemperature is equal to or greater than 50° C. The pre-treatmenttemperature is generally equal to or lower than 120° C. More preferably,the pre-treatment temperature is equal to or lower than 110° C. Evenmore preferably, the pre-treatment temperature is equal to or lower than100° C. Most preferably, the pre-treatment temperature in a range offrom 65° C. to 95° C.

In step (a), the polymer composition comprising amylose and/oramylopectin is generally pre-treated during a reaction time of equal toor greater than 1 minute. More preferably, the pre-treatment reactiontime is equal to or greater than 3 minutes. Even more preferably, thepre-treatment reaction time is equal to or greater than 5 minutes. Thepre-treatment reaction time is equal to or lower than 8 hours. Morepreferably, the pre-treatment reaction time is equal to or lower than 4hours. Even more preferably, the pre-treatment reaction time is equal toor lower than 2 hours. Most preferably, the pre-treatment reaction timein a range of from 1 minute to 30 minutes.

Notably the viscosity of the acylated polymer composition comprisingamylose and/or amylopectin is influenced by the choice of temperatureand reaction time in step (a). For high viscosity of the acylatedpolymer composition comprising amylose and/or amylopectin, lowertemperatures and/or shorter reaction times are suitably selected. Forlow viscosity, higher temperatures and/or longer reaction times aresuitably selected.

In one embodiment of the invention, step (a) and subsequent reactionsteps (b) (and (c), where applicable) are carried out in the presence ofa carboxylic acid RC(O)OH. In this embodiment, the carboxylic acidRC(O)OH is added as reaction medium. Preferably, the acyl-group of thecarboxylic acid RC(O)OH corresponds to the acyl-group transferred by theacylating agent. More preferably, the acylating agent is a symmetricalcarboxylic acid anhydride of formula (RC(O))₂ 0 and the carboxylic acidserving as reaction medium has the formula RC(O)OH, wherein R is definedas above, and RC(O) is the same in the carboxylic acid anhydride andcarboxylic acid that serves as reaction medium. Most preferably, theacylating agent is acetic acid anhydride, and the carboxylic acid whichserves as reaction medium is acetic acid. In this embodiment, generallythe amount by weight of RC(O)OH added in step (a) is approximately equalto the amount by weight of starch, subtracting the potentially presentmoisture in the starch from the amount of starch in the calculation.Preferably, the amount of RC(O)OH is equal to or greater than 80 weight%. More preferably, the amount of RC(O)OH is equal to or greater than 90weight %. Most preferably, the amount of RC(O)OH is equal to or greaterthan 95 weight %. Preferably, the amount of RC(O)OH is equal to or lessthan 120 weight %. More preferably, the amount of RC(O)OH is equal to orless than 110 weight %. Most preferably, the amount of RC(O)OH is equalto or less than 105 weight %. In a most preferred embodiment of thisinvention, the amount of RC(O)OH added in step (a) is from 95 to 105weight %. Generally, more than one carboxylic acid RC(O)OH can bepresent in step (a).

According to the present invention, the amount of water in the aqueousphase present in step (a) is generally equal to or greater than 5 weight%, based on the amount of starch. For this purpose, the weight of anywater present in the starch before step (a) is not taken into accountwhen calculating the ratio of water to starch. Preferably, the amount ofwater is equal to or greater than 6 weight %. Most preferably, theamount of water is equal to or greater than 10 weight %. Generally, theamount of water in the aqueous phase present in step (a) is equal to orless than 30 weight %. Preferably, the amount of water is equal to orless than 25 weight %. Most preferably, the amount of water is equal toor less than 20 weight %. In a most preferred embodiment of theinvention, the amount of water in the aqueous phase present in step (a)is from 10% to 20%.

According to the present invention, the pre-treated polymer compositioncomprising amylose and/or amylopectin of step (a) is reacted with anacylating agent in step (b). As outlined above, an acylating agent isintended to denote a reactant which is capable of reacting with thehydroxyl groups of the glucose units of the starch, thereby transferringan acyl group —C(O)R, —C(O)R′ and/or —C(O)R″ to form the acylatedstarch. Acylation agents may be, for example, carboxylic acid anhydrides(RC(O))₂O, but also unsymmetrical carboxylic acid anhydridescorresponding to the formula (RC(O))(R″C(O))O. Other suitable acylatingagents comprise carboxylic acid halides or carbonylimidazoles.Generally, more than one acylating agent may be present in step (b).

This invention also relates to the formation of mixed acylated starch,where “mixed” is intended to denote more than one acylating agentpresent in the reaction, or a carboxylic acid R′C(O)OH is present in theacylation reaction with (R″C(O))₂O. In one embodiment, the acylation iscarried out with the acylating agent (R″C(O))₂O in the presence ofR′C(O)OH to give ST(OH)_(3-x-y)(OC(O)R′)_(x)(OC(O)R″)_(y). Again, DS(x+y) in the final product is usually from 2.1 to 2.9. R′ and R″ denoteindependently from another the same as R above.

In one embodiment, the acylating agent is an unsymmetrical carboxylicacid anhydride (RC(O))(R″C(O))O, wherein R is not identical with R″, andwherein mixed acylated starches are formed of the formula.

ST(OH)_(3-x-y)(OC(O)R′)_(x)(OC(O)R″)_(y) with a DS=(y+x), which isusually from 2.1 to 2.9 are formed in the final product, and wherein Rand R″ are defined as above.

In a preferred embodiment, symmetrical carboxylic acid anhydrides areused as acylating agent. More preferably, R in (RC(O))₂O is —C₂H₅,—CH₂CH₂F, —CH₂CHF₂ or —CH₂CF₃, meaning that the carboxylic acidanhydrides are selected from the group comprising acetic acid anhydride,difluoro acetic acid anhydride and trifluoro acetic acid anhydride. Mostpreferably, the acylating agent is acetic acid anhydride.

In the specification, the term “acylating agent” is intended to includethe term “one or more acylating agents”.

According to the present invention, the acylating agent is generallyadded in step (b) at a reaction temperature of equal to or greater than40° C. More preferably, the acylating agent is added in step (b) at areaction temperature of equal to or greater than 50° C. Most preferably,the acylating agent is added in step (b) at a reaction temperature ofequal to or greater than 60° C. Generally, the acylating agent is addedin step (b) at a reaction temperature of equal to or lower than 100° C.More preferably, the acylating agent is added in step (b) at a reactiontemperature of equal to lower than 90° C. Most preferably, the acylatingagent is added in step (b) at a reaction temperature of equal to orlower than 80° C. In a most preferred embodiment, the acylating agent isadded in step (b) at a reaction temperature from 62 to 78° C. In orderto control the temperature during the exothermic acylation step, theacylating agent may be cooled before addition to the reaction mixture,for example to a temperature of from 3 to 10° C.

According to the present invention, the reaction mixture in step (b)after the addition of the acylating agent is generally heated for equalto or longer than 10 minutes. More preferably, the mixture in step (b)after the addition of the acylating agent is heated for equal to orlonger than 20 minutes. Even more preferably, the mixture in step (b)after the addition of the acylating agent is heated for equal to orlonger than 30 minutes. Generally, the reaction mixture in step (b)after the addition of the acylating agent is heated for equal to or lessthan 5 hours. More preferably, the mixture in step (b) after theaddition of the acylating agent is heated for equal to or less than 4hours. Even more preferably, the mixture in step (b) after the additionof the acylating agent is heated for equal to or less than 3 hours. Theend point for the heating of the acylation reaction mixture in step (b)generally is indicated by complete or substantially complete dissolutionof the slurry formed initially in step (a), indicating a complete orsubstantially complete acylation of the hydroxyl groups in the starch toa DS of equal to or more than 2.8, or, preferably, more than 2.9 in step(b). In a most preferred embodiment, the reaction time for the acylationreaction in step (b) is from 30 minutes to 3 hours.

According to the present invention, the reaction temperature at whichthe reaction mixture is kept in step (b) after addition of the acylatingagent, is generally equal to or higher than 40° C. More preferably, thereaction temperature at which the reaction mixture is kept in step (b)after addition of the acylating agent, is equal to or higher than 50° C.Even more preferably, the reaction temperature at which the reactionmixture is kept in step (b) after addition of the acylating agent, isequal to or higher than 55° C. Generally, the reaction temperature atwhich the reaction mixture is kept in step (b) after addition of theacylating agent, is equal to or lower than 120° C. More preferably, thereaction temperature at which the reaction mixture is kept in step (b)after addition of the acylating agent, is equal to or lower than 110° C.Even more preferably, the reaction temperature at which the reactionmixture is kept in step (b) after addition of the acylating agent, isequal to or lower than 100° C. Most preferably, the reaction temperatureat which the reaction mixture is kept in step (b) after addition of theacylating agent, is from 60° C. to 90° C.

In the specification, “amount of acylating agent” or “molar ratio ofpolymer composition comprising amylose and/or amylopectin to acylatingagent” also denotes the sum of amounts of acylating agents used in step(b), when more than one acylating agent is used.

According to the present invention, complete or substantially completeacylation of the polymer composition comprising amylose and/oramylopectin can be achieved in step (b), with a DS of equal to orgreater than 2.8, or, more preferably, 2.95. Accordingly, the molarratio of acetylating agent and polymer composition comprising amyloseand/or amylopectin is selected. For the calculation, the molar weight ofthe polymer composition comprising amylose and/or amylopectin isequalized with that of its repeating unit anhydroglucose. In the case ofunmodified polymer composition comprising amylose and/or amylopectin,each mole of anhydroglucose bears basically three free hydroxyl groupswhich are acylated. Generally, the molar ratio of acylating agent topolymer composition comprising amylose and/or amylopectin in step (b) isequal to or higher than 3:1. Preferably, the molar ratio of acylatingagent to polymer composition comprising amylose and/or amylopectin instep (b) equal to or higher than 4:1. Even more preferably, the molarratio acylating agent to polymer composition comprising amylose and/oramylopectin in step (b) equal to or higher than 4.5:1. According to thepresent invention, the molar ratio of acylating agent to polymercomposition comprising amylose and/or amylopectin in step (b) equal toor lower than 19:1. Preferably, the molar ratio of polymer compositioncomprising amylose and/or amylopectin to acylating agent in step (b) isequal to or lower than 1:8. Even more preferably, the molar ratio ofacylating agent to polymer composition comprising amylose and/oramylopectin in step (b) equal to or lower than 7:1. Most preferably, themolar ratio of acylating agent to polymer composition comprising amyloseand/or amylopectin is from 4:1 to 5.5:1.

Additional acylating agent may be present in step (b) corresponding tothe amount of water present, and such excess of acylating agent isselected accordingly in addition to the molar ratio respective to thepolymer composition comprising amylose and/or amylopectin.

According to the present invention, after completed acylation reactionin step (b), which is indicated by complete or substantially completedissolution of the reactants, the reaction mixture of step (b) issuitably cooled to a temperature of from 40° C. to 70° C. Morepreferably, the reaction mixture is cooled to a temperature of from 45°C. to 65° C. To the reaction mixture, suitably a solution of carboxylicacid RC(O)OH, wherein the acyl residue of the carboxylic acidcorresponds to at least one acyl residue of the at least one acylatingagent of step (b), in water is added. By this, any excess of theacylating agent is converted into its corresponding carboxylic acid.

Generally, the DS of the acylated polymer composition comprising amyloseand/or amylopectin as obtained by consecutive steps (a) and (b) is equalto or greater than 2.8, and often greater than 2.95. It has been found,surprisingly, that the treatment of the acylated polymer compositioncomprising amylose and/or amylopectin obtained by consecutive steps (a)and (b) with an acid A′ in a step (c) in order to obtain an acylatedpolymer composition comprising amylose and/or amylopectin with a DS offrom 2.1 to 2.9 has beneficial impact on the solubility of the acylatedpolymer composition comprising amylose and/or amylopectin. Such anacylated polymer composition comprising amylose and/or amylopectindisplays a good solubility in a large variety of aprotic solvents suchas esters, while simultaneously having a high EtOH tolerance. This is anunexpected characteristic of the acylated polymer composition comprisingamylose and/or amylopectin obtainable by consecutive steps (a), (b) and(c), which cannot be achieved by e.g. partial acylation in step (b).

Consequently, according to a preferred embodiment of the presentinvention, the acylated polymer composition comprising amylose and/oramylopectin in the reaction mixture of consecutive steps (a) and (b) isthus reacted with at least one acid A′ in step (c). In thespecification, “acid A′” is intended to denote also “at least one acidA′”, including more than one acids A′. Acid A′ is defined to be an acidhaving a pKa of equal to or less than 4.8 at 25° C. Generally, the acidA′ having a pKa of equal to or less than 4.8 at 25° C. is selected fromthe group consisting of mineral acids, sulfonic acids and carboxylicacids. Acid A′ can be either monoprotic or polyprotic. If acid A′ ispolyprotic, at least pKa₁ is equal to or less than 4.8 at 25° C.Preferably, acid A′ is selected from the group consisting of sulfuricacid, amidosulfonic acid, methane sulfonic acid, benzene sulfonic acidor phosphoric acid. Most preferably, acid A′ is selected from the groupconsisting of sulfuric acid and benzene sulfonic acid. Generally, morethan one acid A′ can be added in step (c).

According to the present invention, the acid A′ in step (c) is generallyadded to the reaction mixture at a temperature of equal to or higherthan 40° C. Preferably, the acid A′ in step (c) is added to the reactionmixture at a temperature of equal to or higher than 50° C. Even morepreferably, the acid A′ in step (c) is added to the reaction mixture ata temperature of equal to or higher than 60° C. Generally, the acid A′in step (c) is added to the reaction mixture at a temperature of equalto or lower than 100° C. Preferably, the acid A′ in step (c) is added tothe reaction mixture at a temperature of equal to or lower than 98° C.Even more preferably, the acid A′ in step (c) is added to the reactionmixture at a temperature of equal to or lower than 95° C. In a mostpreferred embodiment, the acid A′ in step (c) is added to the reactionmixture at a temperature of from 65° C. to 95° C.

According to the present invention, acid A′ is added in step (c) in anamount of equal to or greater than 0.002 weight %, based on the amountof polymer composition comprising amylose and/or amylopectin provided tostep (a). For this purpose, the weight of any moisture present in thepolymer composition comprising amylose and/or amylopectin before step(a) is not taken into account when calculating the ratio of acid topolymer composition comprising amylose and/or amylopectin. If more thanone acid A′ is added in step (c), the sum of weight percentages of themore than one acids A′ is the same as the weight percentage denoted inthe specification for a single acid A′. Preferably, acid A′ is added instep (c) in an amount of equal to or greater than 0.01 weight %. Mostpreferably, acid A′ is added in step (c) in an amount of equal to orgreater than 0.1 weight %. Generally, acid A′ is added in step (c) in anamount of equal to or less than 5 weight %. Preferably, acid A′ is addedin step (c) in an amount of equal to or less than 2 weight %. Mostpreferably, acid A′ is added in step (c) in an amount of equal to orless than 1 weight %. In a most preferred embodiment of this invention,the amount of acid A′ added in step (c) is from 0.2 to 0.8 weight %.

After addition of acid A′, the reaction mixture is usually kept at theaddition temperature as defined above, for a time defined below as “postaddition heating time”.

The post-addition heating time in step (c) is chosen according to theintended DS of the final acylated polymer composition comprising amyloseand/or amylopectin. Longer post-addition heating times will result inlower DS values. Generally, the post-addition heating time is equal toor longer than 10 minutes. Preferably, the post-addition heating time isequal to or longer than 20 minutes. Even more preferably, thepost-addition heating time is equal to or longer than 30 minutes.According to the present invention, the post-addition heating time isequal to or less than 10 hours. Preferably, the post-addition heatingtime is equal to or less than 9 hours. Even more preferably, thepost-addition heating time is equal to or less than 8 hours. In a mostpreferred embodiment, the post-addition heating time is from 50 minutesto 6 hours.

In step (c), the reaction time, temperature and amount of A′ is chosensuch that the DS of the final product is equal to or higher than 2.05.Preferably, the DS after step (c) is equal to or higher than 2.08. Evenmore preferably, the DS after step (c) is equal to or higher than 2.1.According to the present invention, the DS after step (c) is equal to orlower than 2.95. Preferably, the DS after step (c) is equal to or lowerthan 2.92. Even more preferably, the DS after step (c) is equal to orlower than 2.9. In a most preferred embodiment, the DS after step (c) isfrom 2.1 to 2.9.

It should be noted that the total amount of water present in thereaction mixture before the addition of acid A′ in step (c) ispreferably from 5 to 20%, and should suitably be adjusted accordingly ifnot already achieved.

According to the present invention, the acylated product is preferablyrecovered after step (c) by precipitation in water. Further isolationsteps may comprise, e.g., washing, filtering, spinning, pressing, dryingand/or milling.

In one embodiment of the present invention, any of the steps (a), (b)and (c) individually or in any combination may be performed in thepresence of additional solvents, reactants or reagents, such as organicsolvents like dichloromethane or toluene.

According to another embodiment, at any time during the processaccording to the present invention, solvents, reactants or reagents arerecovered from the process for further use.

The pKa value, known as acid dissociation constant, of acid A may bedetermined by standard potentiometric titration procedure.Alternatively, NMR or UV determination methods can be employed for pKadetermination.

The DS value is measured by the following method: The acylated polymeris reacted with sulfuric acid for a time of from 15 to 30 hours at atemperature of from 18 to 23° C. The reaction mixture is subjected to asteam distillation, preferably in an automated distillation apparatussuch as Vapodest 40s (Gerhardt Analytical Systems). The distillate istitrated with NaOH. The DS can be calculated from the amount of NaOHwhich is needed to neutralize the distillate.

The EtOH tolerance is a solubility parameter. It describes the amount ofethanol which is necessary to precipitate a defined amount of a product,in this case the acylated starch, from a solution of a definedconcentration in which the acylated starch is completely dissolved,preferably a solution in an aprotic solvent such as ethyl acetate. Thehigher the EtOH tolerance, the higher the tolerance of the producttowards a protic solvent in the presence of an aprotic solvent.Generally, acylated starches are either soluble in protic or aproticsolvents. It has been found, surprisingly, that the acylated starchesobtained by the process according to the present invention display agood solubility towards aprotic solvents while simultaneously toleratingprotic solvents. This makes the acylated starches according to thepresent invention very suitable for use in inks, varnishes, lacquers,coatings, thickeners, adhesives or binders, which all use a largevariety of different solvent systems.

EtOH Tolerance is measured in a turbidity titration using a T70Titration Excellence Line of Mettler Toledo with a DP5-Phototrode.

For the titration a 10% solution of acylated polymer compositioncomprising amylose and/or amylopectin in EtOAc is prepared, and a sampleof 25 mL of this 10% solution in EtOAc is automatically titrated withEtOH at 25° C. EtOAc is intended to denote ethyl acetate.

For acylated polymer compositions comprising amylose and/or amylopectinwith a DS from 2.1 to 2.45, the end point of the titration is a solidcontent of precipitated acylated polymer composition comprising amyloseand/or amylopectin between 3.7% to 4.7%. The EtOH tolerance in this DSrange for the acylated polymer comprising amylose and/or amylopectinaccording to the present invention is from 53% (v/v) to 63 (v/v). Thisdenotes that 3.7% to 4.7% of the acylated polymer precipitates in asolution of from 53% (v/v) of EtOH in EtOAc to 63% (v/v) of EtOH inEtOAc. This also relates to the EtOH-dilutibility of the acylatedpolymer, which is further described below. The EtOH dilutibility in theDS range from 2.1 to 2.45 for the acylated polymer comprising amyloseand/or amylopectin according to the present invention is from 1.12 to1.7.

For acylated polymer compositions comprising amylose and/or amylopectinwith a DS from 2.46 to 2.9, the end point of the titration is a solidcontent of precipitated acylated starch between 4.4% to 9.5%. The EtOHtolerance in this DS range is equal to or lower than 60% (v/v).Preferably, the EtOH tolerance in this DS range is from 5% (v/v) to 56%(v/v). This also relates to the EtOH-dilutibility of the acylatedpolymer, which is further described below. The EtOH dilutibility in theDS range from 2.46 to 2.9 for the acylated polymer comprising amyloseand/or amylopectin according to the present invention is equal to orlower than 1.5. Preferably, the EtOH dilutibility in this DS range isfrom 0.05 to 1.27.

The EtOH tolerance is an alternative way to describe the“non-solvent-dilutibility”, here EtOH dilutibility, of the acylatedcompositions comprising amylose and/or amylopectin in a solvent in whichthe polymer can be well solved, which is in this case EtOAc. A solutionconsisting of acylated polymer and EtOAc is titrated against a polarsolvent, often water, but in the present invention EtOH, which will notsolve the polymer and is the non-solvent. The polymer compositioncomprising amylose and/or amylopectin in EtOAc is titrated against EtOHuntil turbidity is observed as described above, indicating flocculationof polymer precipitating out of the titrated polymer composition inEtOAc. The non-solvent-dilutibility is a term known is the literature,e.g. in J. Prieto and J. Kiene, “Holzbeschichtung”, p. 61, 2007,published by Vincentz Network GmbH (ISBN 3-87870-749-5) where it isidentified by the german term “Verschneidbarkeit”, which is defined asthe amount of non-solvent, in the present invention EtOH, which can beadded to a solution of polymer in an amount of solvent, which is EtOAcin the present invention, until gelatinization or flocculation isobserved. For example, a dilutibility of 1,12 indicates that up to 1.12parts of EtOH can be added to the solution containing acylated polymercomprising amylose and/or amylopectin and 1 part EtOAc untilprecipitation is observed. The dilutibility as used in the presentinvention not only indicates the suitability of the solvent for a givenpolymer, but, for a given non-solvent/solvent system at a givenconcentration and temperature, also the tolerance of a polymer againstthe non-solvent in its solvent. This characteristic not only related tothe DS of a polymer composition comprising amylose and/or amylopectin,but presumably is also directly dependent on the substitution pattern ofthe hydroxyl-group of the polymer composition, which is effectivelycontrolled in the process according to the present invention. Theviscosity of a fluid is a measure of its resistance to gradualdeformation by shear stress or tensile stress. For liquids, itcorresponds to the informal notion of “thickness”. Solutions of anacylated polymer composition comprising amylose and/or amylopectin canalso be characterized by their viscosity, which is mainly dependent onthe physical and chemical properties of the acylated polymer compositioncomprising amylose and/or amylopectin, when viscosities of the sameconcentration, in the same solvent and at the same temperature arecompared. It has been found, surprisingly, that the viscosity of theacylated polymer composition comprising amylose and/or amylopectinaccording to the present invention can be influenced in a desirablerange by setting reaction parameters accordingly, notably the parametersof step (a). This makes the acylated polymer composition comprisingamylose and/or amylopectin according to the present invention verysuitable for use in inks, varnishes, lacquers, coatings, thickeners,adhesives or binders, which all use a large variety of different solventsystems and have various specific viscosity requirements in thosesolvent systems.

The acylated polymer compositions comprising amylose and/or amylopectinobtainable by the process according to the present invention possess aviscosity, measured in a 10% (w/w) solution in Triacetin at 30° C. witha rotational viscosimeter, such as Rheomat R180 (ProRheo), of equal toor greater than 77 mPas. Preferably, the viscosity is equal to or largerthan 100 mPas. Even more preferably, viscosity is equal to or largerthan 200 mPas. Generally, the viscosity is equal to or lower than 2200mPas (measured in a 20% (w/w) solution in 16 w % EtOH in EtOAc at 30°C.); preferably, the viscosity is equal to or lower than 2100 mPas. Mostpreferred is a viscosity of equal to or lower than 2000 mPas.

According to one preferred aspect, the process according to the presentinvention is carried out in a continuous mode. In another aspect, it canbe advantageous to operate one or more steps of the present invention ina batch-wise mode.

Should the disclosure of any patents, patent applications, andpublications which are incorporated herein by reference conflict withthe description of the present application to the extent that it mayrender a term unclear, the present description shall take precedence.

EXAMPLES Example 1

20 kg of waxy maize with a moisture content of 12.1 weight was reactedwith 17 l of glacial acetic acid, 40 g of sulphuric acid and a mixtureof 40 g of a malonic acid (50 weight % solution in water) and 15 g ofMgCO3 (30 weight % suspension in water during 1.5 h at a temperature of75° C.

58 l of acetic anhydride (91.2% w/w, T=8° C.) were added in portions(approx. 2-5 l) during 1.2 h. The reaction temperature was kept between75 and 90° C. After 3 h the starch acetate was completely dissolved. Thereaction mixture was cooled down to 50° C. 7 l of 56.5% w/w acetic acidin water were added. Afterwards 5-25 l portions of the reaction mixturewere poured in approx. 100 l of cooled water to precipitate the product.

The precipitated powder was washed until no acetic acid was detectable.

The starch acetate powder was pressed of to a solid content of approx.20 weight % and dried to a moisture content of approx. 0.5-3 weight %.

The characteristics of the starch acetate obtained were as following:

-   DS=2.98-   Viscosity (10 weight % in triacetine, 30° C.) 100 mPas-   Soluble in ethylacetate, triacetine, chloroform

Example 2

In example 1, after the acetylation reaction is stopped by addition of56.5% w/w acetic acetic acid in water, a water content of 10-12 weight %was adjusted in the reaction mixture, the reaction mixture was heated upuntil a temp. between approx. 70-95° C. and 0.002 weight % ofconcentrated sulphuric acid (95-98% w/w) was added. In 1-10 h a seriesof different DS (substitution degree 2.9-1.6) was obtained.

Example 3

10 kg of waxy maize with a moisture content of 12.4 weight was reactedwith 12 l of glacial acetic acid and 70 g of benzene sulfonic acid (75weight % in water) during 1.5 h at a temperature of 75° C.

67 l of acetic anhydride (91.2% w/w, T=8° C.) were added in portions(approx. 2-5 l) during 1.2 h. The reaction temperature was kept between75 and 90° C. After 3 h the starch acetate was completely dissolved. Thereaction mixture was cooled down to 50° C. 10 l of 56.5% w/w acetic acidin water were added.

Afterwards, a water content of 8-12 weight % was adjusted in thereaction mixture, the reaction mixture was heated up until a temp.between approx. 70-95° C. and 0.2 weight % of concentrated sulphuricacid (95-98% w/w) was added. Afterwards 5-25 l portions of the reactionmixture were poured in approx. 100 l of cooled water to precipitate theproduct.

The precipitated powder was washed until no acetic acid was detectable.

The starch acetate powder was pressed of to a solid content of approx.20 weight % and dried to a moisture content of approx. 0.5-3 weight %.

In 1-10 h a series of different DS (substitution degree 2.9-1.6) wasobtained.

-   Viscosity (35 weight % in ethylacetate, 25° C.) 379 mPas, DS=2.7;-   Soluble in ethylacetate, triacetine, chloroform.

1-16: (canceled)
 17. A process for manufacturing an acylated polymercomposition comprising amylose and/or amylopectin, having a viscosity ofequal to or greater than 77 mPas (10 w % in Triacetin at 30° C.), whichcomprises: (a) pre-treating a polymer composition comprising amyloseand/or amylopectin with an aqueous phase comprising one additiveselected from the group consisting of at least one acid A having a pKaof equal to or less than 4.8 at 25° C. and an enzyme, and additionallyat least one salt and at least one polycarboxylic acid; and (b) reactingthe pre-treated polymer composition with an acylating agent to providean acylated polymer composition comprising amylose and/or amylopectin.18. The process according to claim 17 further comprising: (c) reactingthe acylated polymer composition obtained in step (b) with at least oneacid A′ with a pKa of equal to or less than 4.8 at 25° C., in thepresence of water.
 19. The process of claim 17, wherein in step (a) thepolymer composition comprising amylose and/or amylopectin is pre-treatedat a temperature in a range of from 20° C. to 85° C. during apre-treatment time in a range of from 1 minutes to 30 minutes.
 20. Theprocess according claim 18, wherein the at least one acid A used in step(a) and the at least one acid A′ used in step (c) can be the same ordifferent and are selected from the group consisting of mineral acids,sulfonic acids, and carboxylic acids, all of which are either monoproticor polyprotic.
 21. The process according to claim 17, wherein the atleast one polycarboxylic acid has from 2 to 12 carbon atoms, and atleast two carboxylic acid groups —COOH.
 22. The process according toclaim 17, wherein the salt consists of a metal cation species and aninorganic or organic anion species.
 23. The process according to claim18, wherein the additive is an enzyme, and wherein acid A′ in step (c)is selected from the group consisting of mineral acids, sulfonic acidsand carboxylic acids, all of which are either monoprotic or polyprotic.24. The process according to claim 17, wherein the acylating agent isselected from the group consisting of carboxylic acids, symmetrical orunsymmetrical carboxylic acid anhydrides, carboxylic acid halides, andcarboxylic acid carbonylimidazoles.
 25. The process according to claim17, wherein step (a) is carried out in the presence of a monocarboxylicacid, wherein the monocarboxylic acid corresponds to the carboxylic acidobtained by hydrolysis of the acylating agent.
 26. The process accordingto claim 17, wherein the polymer composition comprising amylose and/oramylopectin provided in step (a) is selected from the group consistingof chemically modified starches, unmodified starches, and a mixture ofchemically modified starches and unmodified starches, and wherein thechemically unmodified starch is selected from the group consisting ofmaize starch, wheat starch, potato starch, rice starch, pea starch, ryestarch, millet starch, and manioc starch, and wherein the chemicallymodified starch is selected from the group consisting of chemicallymodified maize starch, chemically modified wheat starch, chemicallymodified potato starch, chemically modified rice starch, chemicallymodified pea, chemically modified rye starch, chemically modified milletstarch, and chemically modified manioc starch.
 27. The process accordingto claim 26, wherein the chemically modified starch is selected from thegroup consisting of crosslinked starches, acylated starches,hydroxyethylated starches, hydroxypropylated starches, methylatedstarches, oxidized starches, and cationic or anionic starches.
 28. Theprocess according to claim 17, wherein the time and temperature of thepre-treatment are selected such that the viscosity of the final acylatedpolymer composition comprising amylose and/or amylopectin is equal to orgreater than 77 mPas (10 w % in Triacetin at 30° C.).
 29. The processaccording to claim 18, wherein the reaction time and reactiontemperature of step (c) is selected such that the degree of substitution(DS) of the acylated polymer composition comprising amylose and/oramylopectin is from between 2.0 to 2.9.
 30. An acylated polymercomposition comprising amylose and/or amylopectin, which is made by aprocess comprising the following steps: (a) pre-treating a polymercomposition comprising amylose and/or amylopectin with an aqueous phasecomprising one additive selected from the group consisting of at leastone acid A having a pKa of equal to or less than 4.8 at 25° C. and anenzyme, and additionally at least one salt and at least onepolycarboxylic acid; (b) reacting the pre-treated polymer compositionwith an acylating agent to provide an acylated polymer compositioncomprising amylose and/or amylopectin; and (c) reacting the acylatedpolymer composition obtained in step (b) with at least one acid A′ witha pKa of equal to or less than 4.8 at 25° C., in the presence of water.31. An acylated polymer composition comprising amylose and/oramylopectin, having a degree of substitution (DS) in the range of from2.1 to 2.9, wherein the viscosity of polymer composition is equal to orgreater than 77 mPas (10 w % in Triacetin at 30° C.) and which has aEtOH tolerance of equal to or lower than 60% (v/v).
 32. A process ofmanufacturing inks, varnishes, lacquers, coatings, thickeners,adhesives, or binders comprising the acylated polymer compositionaccording to claim 30 as an ingredient in the process.
 33. The processaccording to claim 20, wherein the at least one acid A and the at leastone acid A′ are the same or different, and are sulfuric acid,amidosulfonic acid, benzene sulfonic acid, or phosphoric acid.
 34. Theprocess according to claim 21, wherein the polycarboxylic acid is atleast one dicarboxylic acid and is selected from the group consisting ofoxalic acid, malonic acid and succinic acid, glutaric acid, and adipicacid.
 35. The process according to claim 22, wherein the metal cationspecies is selected from the group consisting of Mg2+, K+, Zn2+, Na+,Li+, Cu2+, and Ca2+, and the anion is selected from the group consistingof sulfate, nitrate, chloride, carbonate, acetate, and malonate.
 36. Theprocess according to claim 23, wherein the enzyme is an amylase.
 37. Theprocess according to claim 24, wherein the carboxylic acid anhydride isacetic acid anhydride.